A light-fingered cleaner is being blamed for the theft of thousands of pounds worth of antique furniture, art and historic bric-a-brac from the Queensland parliament.

To add to the embarrassment of politicians, staff and security personnel, nobody seems to have missed the fittings and artefacts, which once graced the elegant state parliamentary building in Brisbane's city centre. In fact, nobody is quite sure when they were stolen - they may have been taken nearly 20 years ago.

The theft emerged when a former house attendant informed the Speaker of the Queensland parliament, Tony McGrady, that he had conducted a stocktake of interior furnishings in 1991 and listed dozens of missing items. The official report was then handed to the clerk's office, where it gathered dust and was eventually forgotten until this week.

After the attendant tipped off the Speaker, Mr McGrady obtained his own copy of the inventory, which is now the subject of a police inquiry. Queensland's crime and misconduct commission is also expected to investigate because of the possible involvement of past and present politicians and staff.

Mr McGrady admitted there was a strong possibility the robbery was an inside job. "It would have to be people who worked at Parliament House at the time," he said. Though he could not envisage an MP walking out the front door with a "huge display cabinet or big armchair or couch on his shoulder", he said it was up to police to decide on whether to take the matter further.

While the value of the haul is unclear, the Speaker insisted it did not matter how valuable the items were: "They belong to the people of Queensland [and] Parliament House, which is the people's House, which is what democracy is all about."